Research On Improving The Shear Capacity Of Short And Medium Span Hollow Slab Bridge

Short and medium span hollow slab bridges are widely used in expressways because of their simple structure and convenient construction.With the continuous improvement of load grade and the increasing number of traffic and heavy vehicles,the early hollow slab bridges adopt low load standards or poor environment,resulting in the shear bearing capacity of most hollow slab bridges can not meet the requirements of the current specifications.If this part of hollow slab bridge is demolished and rebuilt,it will not only cause a huge waste of resources,but also affect the normal traffic of vehicles.Based on the actual demand and current situation of short and medium-sized span hollow slab bridges in China,it is very necessary to study and analyze the reinforcement methods to improve the shear capacity of hollow slab bridges.Taking 10 m hollow slab bridge from Linyi to Honghuabu of Beijing Shanghai Expressway as the research object,this paper adopts two methods to improve the shear capacity of hollow slab bridge:thickening the bridge deck pavement and adding diagonal reinforcement in the hinge joint near the bridge fulcrum,the main research contents are as follow:(1)This paper analyzes the causes and mechanism of insufficient shear capacity of hollow slab bridge,and introduces the basic principle and theoretical calculation method of bridge deck pavement reinforcement method and adding inclined reinforcement in the hinge joint near the fulcrum.The internal force of hollow slab bridge is calculated,and it is calculated that its shear bearing capacity does not meet the requirements of the current specifications.(2)In this paper,a total of 4 groups of load tests are carried out with single old hollow beam as the research object,the influence of different deck pavement thickness on the shear capacity of hollow slab beam is studied.Through the comparative analysis of the failure mode,load displacement curve and load strain curve of each test beam,the results show that the deck pavement can participate in the stress together with hollow slab beam,which effectively improves the ultimate shear capacity of hollow slab beam and the shear bearing capacity increases with the increase of the thickness of bridge deck pavement.(3)In order to analyze the effect of adding oblique steel bars in the hinge joints near the fulcrum on the improvement of the shear capacity of hollow slab beams,five groups of load tests are carried out.The test influencing factors include the diameter of reinforcement and the layout spacing of reinforcement.By comparing and analyzing the failure state,load displacement curve and load strain curve of the test beam under different influencing factors,the results show that the addition of diagonal reinforcement in hinged joints can improve the shear capacity of hollow slab beams and the shear capacity increases with the increase of reinforcement diameter and the decrease of reinforcement layout spacing.(4)Using ABAQUS to establish the finite element model of the two reinforcement methods respectively and study the effect of adding different thickness bridge deck pavement and adding diagonal reinforcement to the shear bearing capacity of the hollow slab.It is found that the two methods both can improve the shear capacity of hollow slab bridges,the finite element analysis results are basically consistent with the load test results.